This invention relates generally to improvements in centrifugal pumps. More specifically, but not by way of limitation, this invention relates to submersible centrifugal pumps useful in producing fluids from a well wherein the fluids are laden with sand.
Many wells, oil wells for example, are produced from subterranean zones that are composed of unconsolidated sand. With such unconsolidated sand, the sand grains are picked up in the fluid and passed through a pump which is forcing the oil to the surface from the subterranean zone. Sand is, of course, very hard, and very abrasive and when passing through the normally constructed submersible centrifugal pumps, causes considerable erosion of the parts therein.
One part of such pumps that is very susceptible to wear or erosion from the passage of sand therethrough, is the thrust and radial bearings. In general, a bearing of some type is located between each impeller and its adjacent diffuser. While the bearing is not in the direct flow of fluid through the pump, it is subjected to some flow and to the sand carried thereby. Thus, sand is carried into the proximity of the bearing surfaces.
In the past, the material from which the bearings are constructed has not been as hard as the sand grains and consequently, the bearings were eroded by the sand. Manifestly, the prolongation of the life of a submersible pump is of considerable economic importance since the pump is usually suspended on a tubing string located in a well and the well must be shut down and the tubing string pulled along with the pump in order to repair or replace the pump if erosion takes place.
An object of this invention is to provide a new centrifugal pump having an improved bearing therein that will not be eroded by the presence of sand flowing therethrough.